Drill with novel insert

Abstract

An insert for a drill including a carbide body having a generally polygonal perimeter with three pairs of sides, the sides of each pair being of an equal length.

I claim: 
     
       1. A drill haviing an elongated shank for rotation about a longitudinal axis and having a mounting end and a work end adapted to operate in a cutting plane normal to said longitudinal axis, said drill adjacent said work end having two generally radially extending recesses for the receipt of carbide inserts, said recesses being aligned along a diameter of said shank, each insert including a unitary platelike body having a generally polygonal perimeter, said perimeter being defined by six intersecting sides arranged with alternate sides being longer than the sides intermediate the longer sides, each of said inserts being mounted in its associated recess with the shorter of said sides being adjacent said axis and with said shorter side forming an angle of about 16° relative to said cutting plane and said longer side forming an angle of about 10° relative to said cutting plane whereby cutting forces on said insert are substantially balanced. 
     
     
       2. The drill of claim 1 in which two inserts are mounted in each recess. 
     
     
       3. The drill of claim 1 in which each side is equipped with a step to facilitate chip curl and removal.